Machine-tool control



Dec. 4, 1951 g, JOHNSON 2,577,128

MACHINE TOOL CONTROL Original Filed May 27, 1944 Patented Dec. 4, 19512,577,128 MACHINE-TOOL CONTROL Clarence Johnson, Oriordville, Wis.,assignor to Bailey Meter Company, a corporation of Delaware Originalapplication May 537,606, now Patent No.

Divided and this application Sep- 27, 1944, Serial No. 2,422,682, datedJune tember 6, 1946, Serial No. 695,110

. 7 Claims. 1

This invention relates to duplicators for con trolling the operation ofa material forming machine so that a work piece is formed to a contouror configuration determined by a template, pattern, sample, or the like.

One of the objects of my invention is to improve the sensitivity ofcontour control of the type described, and to thereby increase theaccuracy with which the work piece is formed.

A further object of my invention is to provide a contour control ofmaterially simpler construction than those now available.

In accordance with my invention the pattern or sample for producing thedesired configuration on the work piece is scanned by a tracerregulating a jet of fluid discharged to the atmosphere from a nozzle.Follower means responsive to variations in the shape of the sample causecorresponding changes in the rate of fluid discharged from the nozzle,which fluid discharge rate changes and consequent pressure fluctuationsare then used to control the relative positioning of the tool and workpiece. Further, in accordance with my invention, changes in fluidpressure control the relative positioning of the tool and work piecethrough the agency of a hydraulic relay and servo-motor to the end thatample power is available for accurately positioning the tool relative tothe work piece, or vice versa.

Obviously a duplicator or contour control of the type forming thesubject matter of this invention may be employed with material formingmachines or machine tools of various types, such for example as millingmachines, lathes, slotters, planers, die sinking machines, and othermachines in which the relative feed between the tool and work may besuitably controlled. By way of example I illustrate and will describe myinvention as applied to metal working lathes. Further applications and,modifications of the invention will be readily apparent.

In the drawings:

Fig. 1 is a plan view of an engine lathe illustrating an application ofmy invention thereto.

Fig. 2 is a side elevation of a portion of Fig. 1 and to which has beenadded the fluid pressure and hydraulic circuits interconnecting thevarious portions.

As is well understood by those familiar with the art, in some machinetools, such as lathes, the tool is moved longitudinally and transverselyof the work piece, which except for rotation about its center remainsstationary. In other machine tools, such as some types of millingmachines, the work piece may be moved in two directions, while the toolexcept for rotation about its axis remains stationary. In some othertypes of milling machines, and usually in die sinking machines, the toolmay be moved in one or more directions and the work piece may also bemoved in one or more directions. In all instances it will be observed,however, that it is the relative movement between the tool and workpiece that causes the work piece to be formed to a desired shape. As apreferred embodiment I have chosen to illustrate and describe myinvention incorporated in a lathe wherein the work piece, except forrotation about its center, remains stationary and the tool is movedtransversely and longitudinally thereof. It will be evident that myinvention is applicable to a wide variety of ma-' chine tools and thatwhen I speak of relative movement between the tool and work piece Iinclude either an arrangement where the tool is stationary and the workpiece is moved, or where the work piece is stationary and the tool ismoved, or a combination of the two.

Referring now to Fig. 1, I show my invention applied to an engine latheI having a headstock 2 adapted to be rotated by any suitable means. Acarriage 4 is movable longitudinally along the bed of the lathe insuitable ways 5 and supports the tailstock 3. Also movablelongitudinally along the bed of the lathe in suitable ways 6 is acarriage 1 upon which is mounted a cross-slide 8 movable on ways 8Atransversely of the carriage l, and therefore of the bed of the lathe.

'The cross-slide 8 is provided with an adjustable tool support 9 inwhich is secured a tool l0. Transverse movements of the .tool l0' areproduced through the agency of a hydraulic cylinder ll having a pistonl2 adapted to position the cross-slide 8 along the ways 8A through theagency of a piston rod l3. Longitudinal movements of the tool ID, thatis movements of the tool parallel to thebed of the lathe in alongitudinal direction, are? produced by the usual lead screw M, whichpositions the entire carriage I along the ways 6.

Supported by the headstock 2 and tailstock 3 is a work piece it which,for illustrative purposes, is shown as having been formed to a slender,tapered form by the tool 10. The particular shape has no significance,it being apparent as the description proceeds that by my invention thework piece may be formed automatically to almost any desired contour.The present invention is, however, particularly directed to the formingof work pieces of such a slenderness that during the machining operationthe cutting pressure of the tool may cause a deflection of the workpiece, or wear of the tool may throw an inaccuracy into the finalproduct as compared to the pattern or sample.

Furthermore, the present invention is concerned with the reproduction ofwork pieces from a sample or pattern rather than from a template or cam.Certain objects, .such for example as fuel injection nozzles, can beroughly designed mathematically, but'in final form must be shaped toproduce a result or calibration desired. Such shaping can usually onlybe accomplished by grinding, filing, or turning as calibration proceedsuntil a shape or contour is obtainedwhich will produce the desiredresult or calibration. Thereafter it is desired that this final contouror shape of the sample be reproduced upon numerous nozzles which aredesirably to have the same calibration as the pattern or sample.

In Fig. 1 the sample ll has the contour which it is desired to reproduceupon the work piece [6. The sample I1 is mounted upon centers HA and "Bin axial parallelism with the work piece I8 and in transverse alignmenttherewith.

The present application constitutes a division of my copending PatentNo. 2,422,682, issued June 24, 1947, entitled Machine Tool Control."

Slideable on the cross-slide 8 is a member 15 spring pressed toward theleft (in the drawing, Fig. 2) by a spring 18. The member 15 is movablealong ways 'l'l between stops l8 and 19. Within its limits of travel andunder all normal operating conditions the member I5 has its V edgeengaging a portion of the periphery of the sample 11, as is clearlyillustrated in the drawing.

In similar manner a member 88 is slideable along ways 8| between travellimits l8 and 82 and is normally spring pressed by a spring 83 towardsthe left with its V contact edge engaging a portion of the periphery ofthe work piece l6. Thus under all normal operating conditions the member15 feels the diameter of the sample ll while the member 80 feels thediameter of the work piece IS.

The member 15 forms the housing of an air bleed valve having a stem orcontrolling member 84 adjustably connected to the member 80 by way ofadjustment screw 85. The assembly 15, 84 controls the bleed toatmosphere of air supplied from a pipe 25.

Air under pressure from any convenient source is passed through apressure regulator 22 and through an orifice 28 to the pipe 25. As thedischarge from the assembly 15, 84 to the atmosphere varies, thepressure within the pipe 25 -will vary, and such controlled air pressurerepresentative of the relative positions of the element [5, 84 iseffective upon a bellows 21 of a pilot valve assembly 28. The pilotvalve assembly 28 is more fully illustrated, described and claimed inthe copending applications of Frederick A. Barnes, Patent No. 2,486,097,and of Clarence Johnson, Patent No. 2,475,326.

I show an oil pump 3| driven by a, motor 32 and drawing its supply ofoil from a sump 33. Oil under pressure is supplied the pilot valve 28 bythe pump 3| through a pipe 34. From the pilot valve 28 oil is suppliedto one end or the other of the hydraulic motor I I through the pipes 35or 36. Drainage from the pilot 28 is returned to the sump 33 through apipe 31. The position of the piston rod I3 is determined by the relativeposition of the member 15, 84 and the rate of bleed of air to theatmosphere resulting therefrom.

The operation of this size control arrangement is as follows. Theassembly illustrated in Fig. 2 is traveled by the carriage I (throughthe agency of the lead screw 14) longitudinally of the lathe. If thesample I! is cylindrical, then the relative position of the member 15,84 is unvaried, the bleed of air from the pipe 25 to atmosphere isuniform, the piston rod I3 is stationary, and the cross-slide 8 travelslongitudinally at a uniform normal speed with the tool In cutting thework piece to a cylindrical shape in conformity with the shape of thesample ll.

If for example the sample is tapered with diameter increasing in thedirection of longitudinal travel of the slide 8 (away from the viewer ofFig. 2) then member-15 willbe urged toward the right as the diameter ofsample I'I increases. The movement of member 15 relative to the controlmember 84 varies the discharge to atmosphere of air from the pipe 25 andeffects a con- 4 trol of the servo-motor II in direction to position thepiston rod l3 and cross-slide 8 toward the left whereby the tool illwill cut at an increasingly large diameter on the work piece it. As thediameter of the work piece l6 grows the member is moved toward theright, thus causing a. follow-u of the control member 84 relative to themember 15 to return the bleed of air to the atmosphere toward thepredetermined normal rate, and thus tend to stop movement of the pistonrod l3. If the contour of the sample I1 is a uniform taper the resultingaction will be that the members 15, 84 are continuously a slight amountaway from original position relationship, and therefore resulting in aslight uniform different rate of air discharge from the pipe 25 and auniform continuous movement of the piston rod I3 toward the left. Suchaction resulting from the uniform movement of the tool l0 toward theleft as the assembly travels longitudinally 'along the work pieceresults in a turning of the work piece It to a uniform tapercorresponding to the sample I1. A similar action is obtained if thetaper on the sample I! is uniformly decreasing in diameter away from theviewer of Fig. 2, except that the piston rod I3 is continuously anduniformly moving the tool I toward the right to cut the work piece IE toa uniform taper.

The arrangement provides a continuous size control or check between thediameter at which the tool i0 is cutting the work I8 and the diameter ofthe sample 11. If, due to wear of the tool or for other reasons thediameter of the work It tends to grow slightly while the diameter of thesample [1 has not changed, then the increasin diameter of the work l6positions the control member 84 toward the right in the member 15,resulting in a change in the rate of air bleed to the atmosphere andtherefrom a positioning of the piston rod 13 to the right, whereby thetool ill will turn the work to a slightly smaller diameter, thuscompensating for wear on the tool. As the diameter of the work I6approaches the correct diameter of the sample I! the correctinterrelation between the parts 84 and 15 is attained, and furthermovement of the piston rod I3 is stopped. Thus the arrangement of Fig. 2provides a continuous check of the actual diameter of the work IS withthe desired diameter of the sample I! irrespective of what that latterdiameter may be.

If the cross section of the sample I! is other than a circle at any orall longitudinal points, then desirably the sample ll may be rotatedwith the work I6. Thus an elliptical or similar cross section sample maybe reproduced, and in fact a square, triangular, or other cross sectionsample may be reproduced in the work piece It having proper regard forthe rate of rotation of the work and sample, the rate of longitudinaltravel, the shaping and sharpening of the tool, etc. In other words, thespeed and speed of response of the various moving parts may beconsiderably different in turning a piece having a square cross sectionthan in turning one having a cylindrical cross section. A simple methodfor rotating the sample I! has been diagrammaticall-y shown inFigure 1,and includes a gear is mounted for rotation with the spindle of theheadstock 2. A second gear 2|).is fixedly attached to the sample I1 andis driven from the gear l9 through an idler gear 2|, journaled on anysuitable means not shown; If at any time it is not desired to rotate thesample I'I, then the idler gear 2| may be moved out of engagement withone of the gears l9 or 20.

For the construction, operation and advantageous features of the relay28 and of the bleed valve 15, 84 reference may be had to my copendingapplication, Patent No. 2,475,326, and to the copending application ofFrederick A. Barnes, Patent No. 2,486,097. The construction andoperationalfunction of the bleed valve 15, 84 are substantially the sameas of the tracer assemblies I9 and 68 of my parent Patent No. 2,422,682,of which the present application is a division. A pressure fluid isavailable to the bleed valve assembly at a substantially uniformpressure. Between the supply and the exit of the bleed valve assemblythe pressure of the fluid will vary representatively of the positioningof the valve member 84 in the housing 15, and therefore of the rate ofbleed to atmosphere of said pressure fluid. In the present embodiment Ipreferably use air as such pressure fluid, and discharge this freely tothe atmosphere in accordance with the positioning of the element 84 inthe element 15.

In general it will be seen that the pressure of the fluid which isapplied to the bellows 21 is representative of the position of theelement 84 in the element 15, and therefore is representative of therelation of diameters of the elements 16 and 11. I provide, therefore, acontrol sensi tive to the actual size of the work piece in comparison tothe actual size of the sample. From such control I preferably positionthe tool III in 'proper direction and amount to so form the work piece16 that its diameter will agree with the diameter of the sample I! atthe proper reference point.

While I speak of having the two diameters agree, it will be understoodthat they agree if they are in proper proportion. For example, there maydesirably be a definite scale relationship between the actual dimensionsof i6 and [1.

While I have illustrated and described a preferred embodiment of myinvention, it will be understood that this is by way of example only andnot to be construed as limiting.

What I claim as new, and desire to secure by Letters Patent of theUnited States, is:

1. In a tracer control system for a machine tool having a frame and arelatively movable tool holder and work holder adapted to carry a tooland a workpiece, respectively, a sample having the desired shape of theworkpiece, means for providing two-dimensional relative movement betweensaid tool holder and work holder and including at least one slide onsaid frame, one of said tool holder and work holder being mounted onsaid slide to effect said two-dimensional relative movement, said tracercontrol system including, means supporting said sample on said frame inthe same orientation as said workpiece, a first feeler element slidablymounted on said slide and resiliently urged in a direction to contactsaid workpiece substantially adjacent the cutting position of the tool,a second feeler element slidably mounted on said slide and resilientlyurged in a direction to contact said sample, power means to move saidslide, fluid pressure means interconnected with said power means tocontrol same, a valve housing having an axis, means to move said valvehousing in accordance with movements of one of said feeler elements,said axis being aligned with the transverse motion of the other of saidfeeler elements, a valve member disposed within said valve housing,means to move said valve member in accordance with the movement of saidother of said feeler elements, said valve housing and valve memberincorporated in said fluid pressuremeans and operative to vary thepressure of said for supporting said sample on said frame in axialparallelism with the workpiece, a first feeler element slidably mountedon said cross slide and resiliently urged in a direction to contact saidworkpiece, a second feeler element slidably mounted on said cross slideand resiliently urged in a direction to contact said sample, power meansto move said cross slide. fluid pressure means interconnected with saidpower means to control same, a two-element fluid valve incorporated insaid fluid pressure means and operative to vary the pressure in saidfluid pressure means, said fluid valve including a valve housing and avalve member reciprocable therein, means to move said valve housing inaccordance with the movement of one of said feeler elements, means tomove said valve member in accordance with the movement of said otherfeeler element, said valve housing and valve member varying the fluidpressure of said fluid pressure means in accordance with variations inthe relative shape of said sample and workpiece as said sample istraversed.

3. In a tracer control system for a lathe having a frame and arelatively movable tool holder and work holder adapted to carry a tooland a workpiece, respectively, a sample having the desired shape of theworkpiece, a carriage on said frame positionable axially relative tosaid work holder, a cross slide mounted on and adapted to be movedtransversely of the carriage, the tool holder being mounted on the crossslide, said tracer control system including, means for supporting saidsample on said frame in axial parallelism with the workpiece, means forrotating said sample, a first feeler element slidably mounted on saidcross slide and resiliently urged in a direction to contact saidworkpiece substantially diametrically opposite the tool, a second feelerelement slidably mounted on said cross slide and resiliently urged in adirection to contact said sample, power means to move said cross slide,fluid pressure means interconnected with said power means to controlsame, a two-element fluid valve incorporated in said fluid pressuremeans and operative to vary the pressure in said fluid pressure means,said fluid valve including a valve housing and a valve memberreciprocable therein, means to move said valve housing in accordancewith the movement of one of said feeler elements, means to move saidvalve member alone the axis of said valve housing in accordance with themovement of said other feeler element, said valve housing and valvemember varying the fluid pressure of said fluid pressure means inaccordance with variations in the relative shape of said sample andworkpiece as said carriage is axially moved.

4. In a tracer control system for a lathe having a frame and arelatively movable tool holder and work holder adapted to carry a tooland a workpiece, respectively, a sample having the desired shape of theworkpiece, a carriage on said frame positionable axially relative tosaid work holder, a cross slide mounted on and adapted to be movedtransversely of the carriage, the tool holder being mounted on the crossslide, said tracer control system including, means for supporting saidsample on said frame in axial parallelism with the workpiece, means forrotating said sample, a first feeler element slidably mounted on saidcross slide and resiliently urged in a direction to contact saidworkpiece substantially diametrically opposite the tool, a second feelerelement slidably mounted on said cross slide for translation parallel tosaid first feeler element and resiliently urged in a direction tocontact said sample, power means to move said cross slide, fluidpressure means interconnected with said power means to control same, atwo-element fluid valve incorporated in said fluid pressure means andoperative to vary the pressure in said fluid pressure means, said fluidvalve including a valve housing and a valve member reciprocable therein,means to move said valve housing in accordance with the movement of oneof said feeler elements, means to move said valve member along the axisof said valve housing in accordance with the movement of said otherfeeler element, said valve housing and valve member varying the fluidpressure of said fluid pressure means in accordance with variations inthe relative shape of said sample and workpiece as said carriage isaxially moved.

5. In a tracer control system for a lathe having a frame and arelatively movable tool holder and rotatable work holder adapted tocarry a tool and a workpiece, respectively, a sample having the desiredshape of the workpiece, a carriage on said frame positionable axiallyrelative to said work holder, a cross slide mounted on and adapted to bemoved transversely of the carriage, the tool holder being mounted on thecross slide, said tracer control system including, means for supportingsaid sample on said frame in axial parallelism with-the workpiece, meansfor rotating said sample in timed relation with the rotation of saidworkpiece, a first feeler element slidably mounted on said cross slidefor translation parallel to said cross slide and resiliently urged in adirection to contact said workpiece substantially diametrically oppositethe tool, a second feeler element slidably mounted on said cross slidefor translation parallel to said cross slide and resiliently urged in adirection to contact said sample on substantially the same side of saidsample as said first feeler element contacts said workpiece, power meansto move said cross slide, fluid pressure means interconnected with saidpower means to control same, a two-element fluid valve incorporated insaid fluid pressure means and operative to vary the pressure in saidfluid pressure means, said fluid valve including a cylindrical valvehousing and a valve member reciprocable therein, means to move saidvalve housing parallel to said cross slide movement in accordance withthe movement of one of said feeler elements, means to move said valvemember parallel to said cross slide movement in accordance with themovement of said other feeler element, said valve housing and valvemember varying the fluid pressure of said fluid pressure means inaccordance with variations in the relative shape of said sample andworkpiece as said carriage is axially moved.

6. In a machine tool having a frame and a relatively movable tool andworkpiece, a sample having the desired shape of the workpiece, meanssupporting said sample on said frame in axial parallelism with theworkpiece, a first slide mountedon said frame and adapted to move in afirst direction relative to said frame, a second slide mounted on saidfirst slide and adapted to move transversely of said first direction,one of said tool-and workpiece being mounted on said second slide. aflrst travel rest slidably mounted on said second slide and resilientlyurged into contact with said work substantially diametrically oppositesaid tool, a second travel rest slidably mounted on said second slideand resiliently urged into contact with said sample, power means to movesaid second slide, fluid pressure means interconnected with said pov. ermeans to control same, a two-element fluid valve incorporated in saidfluid pressure means and operative to vary the pressure in saidfluid-pressure means, means to move one of the elements of said valvereciprocably in accordance with movements of said first travel rest,means to move the other of said elements of said valve reciprocablywithin said first valve element in accordance with movements of saidsecond travel rest, said elements of the valve being operativelyinterconnected to vary the said fluid pressure in accordance withvariations in the relative shape of said sample and workpiece as saidfirst slide is moved in said first direction.

7. In a lathe having a frame and a relatively movable tool holder andwork holder and for use with a sample having the desired shape of aworkpiece, said lathe including means for supporting said sample on saidframe in axial parallelism with the work holder, a cross slide on saidframe adapted to be moved transversely of the work holder, the toolholder being mounted on the cross slide, a first feeler element slidablymounted on said cross slide and resiliently urged for contacting theworkpiece held by said work holder, a second feeler element slidablymounted on said cross slide and resiliently urged for contacting saidsample, power means to move said cross slide, fluid pressure meansinterconnected with said power means to control same, a valve housinghaving an axis, means to move said valve housing in accordance withmovements of one of said feeler elements, said axis being aligned withthe transverse motion of the other of said feeler elements, a valvemember disposed within said valve housing, means to move said valvemember in accordance with the movement of said other of said feelerelements, said valve housing and valve member varying the fluid pressureof said fluid pressure means in accordance with variations in therelative shape of said sample and workpiece as said sample is traversed.

CLARENCE JOHNSON.

REFERENCES CITED The following references are of record in the flle ofthis patent:

UNITED STATES PATENTS Number Name Date 2,372,427 Johnson Mar. 2'7, 19472,422,682 Johnson June 24, 1947

